NOAA Researchers May Have More Accurate GHG Measurement Method

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Greenhouse gases are on the on the rise — the data to support that trend have existed for years. But scientists say now that a new method of tracking the effects of the gases could lead to a more accurate understanding of their impact on climate change, which other scientists say the Arctic is already experiencing on a dramatic scale.

Researchers at the National Oceanic and Atmospheric Administration (NOAA) developed what they call a "scientifically unambiguous" index, that they say will allow them to track changes in the gases that contribute the most to the warming greenhouse effect. Their results, released on Sept. 27, confirm that the net effects of these greenhouse gases is increasing.

To create the Annual Greenhouse Gas Index (AGGI), NOAA scientists used measurements of greenhouse gas concentrations, recorded around the world since 1979. They accounted for only the main "long-lived" greenhouse gases that remain in the atmosphere and are uniformly mixed throughout the global atmosphere; those gases include carbon dioxide, methane, nitrous oxide and chlorofluorocarbons. "In this way the index is similar to the Consumer Price Index, which includes the most important commodities that reflect prices best," says David Hofmann, director of the NOAA Global Monitoring Division of the Earth System Research Laboratory in Boulder, Colorado, and a member of the research team that developed the index.

The team converted the concentrations to a measure of how the gases change the difference between the amount of solar radiation entering Earth's atmosphere and the amount of Earth's heat leaving. The resulting index uses data from 1990 for its baseline comparison, which is also the same year that the international Kyoto Protocol uses to measure progress in the reduction of greenhouse gases. A higher AGGI implies a greater change in the amount of heat trapped by greenhouse gases. "The AGGI will serve as a gauge of success or failure of future efforts to curb carbon dioxide and other greenhouse gas increases in the atmosphere," Hofmann says.

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